Within the last decade, active genetic manipulation of mice has fundamentally increased our ability to study development and function. Although interpretation of experiments involving genetic manipulation of mouse embryos must be performed with care, the ability to monitor changes in an entire organism upon modification of a single genes makes this technique an indispensable tool for modern inquiry in neurobiology. The overall goal of core A is to generate and maintain genetically altered mice. An important aspect of the overall goal is to facilitate inquiry by promising junior investigators into the chemical senses. In order to attain this goal, three specific aims are delineated. 1. To produce genetically altered mice. 2. To maintain genetically altered mice. 3. To type offspring of genetically altered mice. Consolidation of these services in a core facility enables individual investigators to more efficiently focus efforts on research questions and is more cost effective than duplication of facilities in individual laboratories. Because the production and maintenance of transgenic/gene-targeted mice is expensive, the services provided by the core are particularly important for the more junior investigators. The core will also be a resource for the scientific community at large because genetically altered mice will be made available following publication.